Investigation on the polyclonal hyperimmunoglobulinemia (PHIg) induced by antigenic challenge are being carried out to determine the mechanism of initiation of the phenomenon as well as the suspected antibody activity of the PHIg. In vitro studies will be used to determine cell types involved in the response, metabolic requirements and relationship of this response to a specific antibody response. In addition, studies are being initiated which are aimed at determining the role of T cells in this B cell phenomenon. Other studies involve an analysis of the PHIg response in other representative vertebrate classes to determine both the phylogenetic hierarchy of the response and the relationship of the PHIg phenomenon to other defense mechanisms. Finally, the age and genetic related aspects of the response as well as the possible role of second messengers (cAMP, cGMP, calcium etc.) in the initiation of the response are being studied.